Animal Body Plans Adapted fromhttp://userwww.sfsu.edu/~biol240 /labs/lab_16animalbodyplan/pages/bo dyplan.html

Metazoans “Animals” – Multi-cellular – Develop from embryos – Divided into two groups based on the presence of a backbone Metazoans

Body Plans This can also be described as way an animal is “built” or the architecture of a species There are some basics features of a body plan that can be used to compare animals The various body plans we will cover have been shaped through evolution and constraints on the animals

Cambrian Explosion Most major animal groups around today originated in the precambrian and cambrian era Explosion of diversity in a relatively short period of time Some major evolutionary branches occurred around symmetry and multicellularity

Embryology – Protostomes-mouth forms first then the anus during embryological development Most invertebrate groups – Deuterostomes- anus forms first then the mouth Can split up cells at 4 cell stage and each will continue to develop into a complete viable organism Echinoderms and chordates

Symmetry Def-pattern of arrangement of body parts Asymmetry- no pattern of symmetry around an axis… – No way to divide the org into similar looking halves Radial-more than one line of bisection Bilateral- one line of bisection ie a distinct right and left side – Also typically have dorsal and ventral surface, anterior and posterior surface

Body Cavity Also called a coelem Fluid filled cavity found between body wall and digestive tract Many different types and ways that a body cavity develops Acts as a hydrostatic skeleton in some less advanced animals

Endoderm Mesoderm Ectoderm Gut Pseudocoel Coelem

Segmentation Repeated grouping of parts or compartments – Aids in movement and evolution of appendages – Groups of segments and their appendages have become specialized for a variety of “jobs” among regions ie a division of labor

Cephalization Def-Having a head – Sensory organs, centralized nervous system and feeding parts are all usually concentrated here – Are there advantages to this arrangement? – Is there a particular kind of symmetry associated with this?

Cephalization Advantage- Anterior end of a travelling animal will encounter stimuli-food, danger etc… first Adaptation for burrowing, crawling, swimming Radial animals tend to be sessile or planktonic- can meet environmental symmetry from all sides Active animals moving in a distinct direction “meet” the environment from one end and bilateral symmetry fits that lifestyle

WORD BANK Symmetry Multicellularity Pseudocoelem Protostome deuterostome Body cavities and blood vascular system Tissues Coelem

Hydrostatic skeleton- skeleton composed of fluid and under pressure in an enclosed body compartment Main skeleton of cnidaria and some worms Gastroderm- layer of tissue producing digestive enzymes